The number’s good except when it’s not

Based on a Hitwise report, Online Media Daily reported that Twitter’s “torrid growth has cooled since April.” But the Hitwise number is deeply flawed – it doesn’t include traffic from “mobile and application-driven traffic.”

In other words, Hitwise’s report is based solely on traffic from Twitter’s web site. It doesn’t include traffic from smartphones and applications like TweetDeck. Hitwise’s report is just not that useful because it doesn’t include traffic from the devices and software that have made Twitter ubiquitous and easy to use, and which probably have contributed greatly to Twitter’s growth.

I say “probably” because we just don’t know one way or another. Everyone’s still trying to figure out how to measure mobile web use. It’s hard because there are multiple carriers and devices. But just because a number is hard to get doesn’t mean we should use a number whose only virtue is that it’s easy.